| China is the biggest epidemic region of Puccinia striiformis West, and can cause sever yield losses in wheat production. Due to the undiscovered sexual phase of P. striiformis West., using wheat differential cultivars becomes the only way of identifying the virulent genes of races. Definite resistant genes and inherit trait of differential cultivars of identifying of P. striiformis West, is one important step which facilitate race identification, monitoring and physiological specialization, and analysis resistant genes in wheat. Five differential cultivars, Montana, Abbonanza, early premium, Fengchan3 and Lovrin 13 contain unknown resistant genes to yellow rust. Traditional genetics, allelic analysis and monosomic analysis were used in this study to assay the number, recessive or dominance, interactions and inherit trait of major genes in those five differential cultivars. Also four races were used to examine differences between resistant genes designated and genes known. To determine the chromosome location of resistant genes in Abbonanza and early premium, those two cultivars were crossed with a set of susceptible Tritici. Spelta aneuploids. As minor genes are sensitive to temperature, seedlings were inoculated with virulent races and tested minor genes in the five cultivars in high temperature.The results show that Abbonanza contains at least two major genes different from named genes which inherit by nucleolus. Also two recessive complementary genes or one recessive and one repressive resistant gene effective against Su-1 and 79009 exist in Abbonanza. The relationships between those genes against Su-1 and 79009 are needed to be certain in the future. Genes against race79009 are located on 3B and 7B chromosomes.Early premium has at least three major genes and inherited by nucleolus. Those genes are different from known major genes. The resistance to CY18 is determined by two recessively complementary genes. Three recessive complementary genes confer resistance to 79009. Chromosomes location of genes against race 79009 is on 3B, 4D and 5D.Fengchan 3 carries at least two major genes and two minor genes, and inherited by nucleolus. Those genes are different from the tested known genes. There are one dominant and one recessive complementary gene effective against CY17. There are two recessive genes overlapped or independent against CY18. Two recessive complementary genes or one recessive and one repressive resistant genes against 79009. In high temperature, the resistance of Fengchan3 to CY26 is controlled by two recessive minor genes. All genes studied are different from the supplied known genes. Further studies are needed to confirm the relationships among those major genes.Mentana has at least three major genes which are different from the known genes used. Results of positive cross indicated that the resistance to Su-1 and 79009 was controlled by three recessive complementary genes. However, the test of reverse cross shown that the resistance was controlled by two dominant and one recessive complementary genes. Positive cross result indicated that two overlapped or independent recessive genes conferring against CY26, while reverse cross indicated that two complementary recessive genes against the race. The results need further studied .The resistance of Lovrin 13 to races CY17, CY26 and Su-1 is controlled by two genes respectivelywhich are inherited by nucleolus. One of the two genes is Yr9 which is allelic or close linkage respectively with Yr10 and Yr24. The other gene to CY 17 is probably located on chromosome 3B. More studies are required to understand whether it is different or not between the other unknown gene to CY26 and Su-1 in Lovrin 13.
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